Electrically actuated contactor



W. G. YOUNG ET AL ELECTRICALLY ACTUATED CONTACTOR March 26, 1946.

Filed Feb. 29, 194-4 w t w 4 m /v 4 wm w H 2 2 M WW m A -r 2 2 I 1 4 M M20 nIlll;

WITNESSES:

Patented Mar. 26, 1946 UNITED STATES PATENT OFFICE ELECTRICALLY ACTUATEDCONTACTOR Application February 29, 1944, Serial No. 524,350

Claims. (01.20047) Our invention relates to electrically actuatedcontactor-s in which a contact carrier is resiliently linked to arocking armature so as to permit the armature to continue its contactclosing motion to a limited extent after the electric contact has beeninitiated by the contact carrier.

During this limited overtravel motion in the known relays of this type,the contact mounted on the carrier performs a sliding or rolling motionrelative to the cooperating stationary relay contact.

It is one of the recognitions underlying this invention that theabove-mentioned phenomenon is apt to increase the electrical stress andwear on contacts of the non-wiping type, thus limiting the useful lifeof the contacts and hence the period of undisturbed relay operation. Thereason for this detrimental effect lies in the fact that the relativemotion between the contacts occurring after the electrical engagementhas been established causes or supports the transfer of contact materialfrom one contact to the other and may also produce slight localsparking, enhancing the transfer effect. This is especially the casewith contacts of silver, or the like highly conductive material as ispreferably employed in circuit-closing contacts, for instance, intime-limit relays,

Therefore, an object of the invention is to provide a relay of the typehere concerned, which affords a considerable increase in the life orundisturbed operating time of the contacts controlled by the relayarmature.

Another object, related to the foregoing is to reduce or substantiallyeliminate the tendency of non-wiping contacts to are or spark and tode-.

velop a transfer of contact material during the overtravel period of thearmature.

According to another object, the invention aims at achieving theseresults by providing a rela in which the overtravel motion of thearmature has no noticeable effect on the motion of the contact memberresiliently assembled with the armature so that sliding, bouncing orrolling motions due to the overtravel motion are prevented.

An object in conjunction with those mentioned is to prevent relativemotion of the rela contacts during the cvertravel period by means ofsimple construction and easy method of assembly so that the desiredadvantages are obtained without drawbacks in other respects.

For achieving these objects, and in accordance with our invention, weprovide a contactor with a contact carrier or contact finger which isresiliently linked to the contactor armature so as to move together withthe armature when the contacts are disengaged, and which engages thestationary or supporting structure of the contactor at a pivot orabutment travel period.

According to a subsidiary feature of the invention, the engagementbetween the contact finger and the stationary structure is establishedslightly previous to the initial engagement between the contacts of thecontactor and remains effective over the entire period of contactclosure.

In another aspect of the invention, the pivot or fulcrum of the contactfinger established by its temporary engagement with the stationarcontactor structure is spaced from the place of dontact engagement andlies close to the plane determined by the pivot axis of the rockingarmature and the place of contact engagement. As a result, any lateralmotion between the contacts is effectively prevented during the periodof overtravel.

According to still another feature of the invention, the contact fingeris located at the side of the armature away from the magnet core of anelectromagnetic contactor and adapted to establish the aforementionedstationary engagement through an opening of the armature. This leads toa construction of especially simple design and permits an easy assemblyand disassembly of the device.

It is also one of the essential features, in a specific aspect of theinvention, to provide the magnet core of a contactor of thejust-mentioned type with means, placed on the front or pole surface ofthe core, for engaging the contact finger, the finger and the core meansbeing shaped with respect to each other so that one of them forms apoint during the overprojection and the other a recess, hole, or grooveto be engaged by the projection.

Still more specifically, a preferred embodiment in accordance with thelast-mentioned aspect employs a knife edge and groove type engagement sothat the contact finger is firmly held against the magnet core duringthe overtravel period.

These and other objects and features of the invention will be apparentfrom the following description of the contactors illustrated in thedrawing, in which:

Figure 1 is a lateral and part sectional view of a completeelectromagnetically actuated contactor according to the invention, thearmature and contact assembly being represented in contactclosingposition.

' Figs. 2 and 3 are partial views of the same device with the armatureand contact assembly in contact opening and intermediate position,respectively.

Fig. 4 is a partial and part sectional side elevation of anotherembodiment of the invention, while Fig. 5 shows a similar elevation of athird embodiment.

Referring to the relay shown in Fig. l, th numeral l denotes an L-shapedmagnetic base structure. An elongated cylindrical magnet core 2 isfirmly attached to the structure I so as to extend in parallel to one ofits legs. A tubular coil carrier 3 of non-magnetic material is placed onthe core 2 and carries the operating coil 4 of the relay. A stationarycontact 5 is mounted on an insulating carrier 6 which, in turn, is firm-1y secured to the base structure H. An abutment plate I is mounted onthe exterior surface of one of the legs of the structure l and projectsover the end of this leg in order to form a dihedral pivot bearing forthe armature. The projecting end of the abutment plate ll carries athreaded bolt 8 which serves as a holder for a coiled compression spring9 whose force is adjustable by means of a nut l engaging the bolt ti.

The armature ll f the relay consists essentially of a fiat plate-shapedstructure and has a beveled end which forms a knife-type pivot edge atH. This pivot edge rests against the angular pivot bearing formed by thestructure l and the abutment plate 1 so that the edge l2 defines theaxis of the pivotal rocking motion of the armature H. A bracket 25 isfirmly attached to the armature II and has an opening traversed by thebolt 8. The bracket 25 serves as an abutment' for the spring 9 so thatthe force of the spring biases the armature ll away from the magnet core2. The upper end of the bracket 25 and the adjacent end of the abutmentplate 1 form also a stop for limiting the spring biased movement of thearmature about the pivot edge l2. A non-magnetic shim plate i3 ismounted on the side of the armature facing the magnet core.

A rigid contact finger M of highly conductive material, such as copper,is resiliently and pivotally linked to the armature in the followingmanner. The finger l4 has a projection 26 which is bent towards themagnet core 2 and projects through an opening iii of the armature. Aguiding member I!) attached to the armature ll surrounds the finger |4so as to prevent it from effecting lateral motions perpendicular to theplane of illustration. A helical compression spring 20 is placed betweenthe guiding member l9 and the finger l4 and tends to hold the finger itagainst the upper surface of the armature ll. Consequently, when thearmature is in the position shown in Fig. 2, the finger l4 lies fiatagainst the armature and participates in the angular pivotal motion ofthe armature without effecting any motion relative to the armature. Acontact'l5 is arranged at the peripheral end of the contact fingerrelative to the just-mentioned pivotal motion and serves to establishelectric contact with the stationary contact when the armature El isattracted by the magnet core 2, as shown in Fig. 1.

A pole plate 2| consisting, for instance, of magnetizable material ismounted on the front or pole surface of the magnet core 2 by means of ascrew 22. The pole plate 2! has a circular groove 23 at its uppersurface which is so located as to be engaged by a knife edge 24 formedby the outermost end of the projection 26.

When the armature is in the contact-opening position shown in Fig. 2,the edge 24 of projection 26 is disengaged from the groove 23 of plate 2I. When the magnet coil 4 is energized, the core 2 attracts the armatureand moves the contact l5 into closing position. During this motion andimmediately previous to the initial en agement between contacts 5 andI5, the armature passes through the position illustrated in Fig. 3. Inthis position, the edge 24 of projection 26 engages the groove 23 ofplate 2|. From this moment on, the further motion of the contact finger14 is limited to a rocking motion about the pivot axis of the engagementat 23 and 24. From the subsequent moment when the contacts l5 and 5establish their initial engagement, the position of contact finger l4and contact l5 relative to the magnet core and the stationary contact 5remains unchanged while the armature ll performs an additional angularmotion towards the magnet core under compression of the spring 20 untilit reaches the final position apparent from Fig. 1.

It Will be noted from the foregoing that due to the temporary pivotalengagement of the contact finger M with a stationary part of the relay,a wiping, rolling or bouncing motion between the relay contacts isprevented, from hortly previous to the initial contact engagement to theend of the contact closing operation without interfering with thefreedom of the armature ll to perform the desired ovcrtravel motionafter establishment of the initial contact engagement.

In the above-described embodiment according to Figs. 1, 2 and 3, thepivot edge 24 of the contact finger I4 is spaced relatively far awayfrom the point of contact engagement. Furthermore, the pivot edge whenin operative engagement with the groove 23 of the pole plate 2| is solocated that it lies approximately in the geometrical plane determinedby the pivot axis of the armature l l and the place of contactengagement between contacts 5 and [5. Due to these features, anyrelative motion of contacts 5 and it within the plane of contactengagement is most effectively prevented.

Due to the location of the contact finger l4 at the armature side awayfrom the magnet core 2, the contact finger and its appertaining partsare easily accessible from the outside so that the assembly ordisassembly of the contact finger from the armature, or of the entirearmature assembly including the contact finger from the stationary relaystructure, is facilitated. The provision of a circular groove in plate2| eliminates the necessity of adjusting the groove 23 relative to thepivot edge 24 of contact finger 14. However, it will be understood thatinstead of acircular groove, a recess or edge of limited length,properly located on pole plate 2!, may also be used. a

The embodiment shown in Fig. 4 represents a relay whose stationarystructure is substantially similar to that of the above-described deviceand hence only partially illustrated in Fig. 4. In this embodiment, themagnet core 2 of the relay energized by the coil 4 and mounted on thestationary structure I carries a conical projection 38 screwed onto thecore 2 by means of-a nut 40 which permits an adjustment of the apex ofthe cone as regards its distance from the core 2. The armature 3|carries on its underside a non-magnetic shim 33 and has a pivot edge 32resting against a dihedral pivot bearingformed by the structure l andthe appertaining abutment plate I. A contact finger 34, carrying amovable contact l5 for engagement with the stationary relay contact 5,

is located on the upper side or the armature 3i and has a projection 37bent downwardly in order to engage a bore 3!) of the armature. Thisengagement as well. as a guiding member as secures the contact finger 34in proper position relative to the armature. it spring it placed betweenthe guiding member ti? and the contact finger til holds the finger inface-to-iace relationship with the armature when the contacts areopened.

The contact finger 3t has a recess or indented portion at $33, which isso located as to be engaged by the conical projection 38 when thecontacts are just about to touch each other, while the armature 3i isattracted by the magnet core 2. As a result, the armature is permittedto perform an additional overtravel motion towards the end positionshown in Fig. 4, while the contact finger is limited to pivotal motionabout the axis of the cone 38 under compression of spring 4 6.

According to the embodiment represented by Fig. 5, the magnet core 2surrounded by the magnetizing coil 4 and mounted on the stationarystructure I of the contactor is provided with a rounded projection 48which is adjustable within limits by means of a screw nut 50. Thearmature 4i is pivoted at 42 in the same way as described in connectionwith the preceding embodiments and carries a non-magnetic shim 43 at itsside facing the magnet core 2. A contact finger 44, consistingsubstantially of a fiat strip element and of sufllcient rigidity toavoid undesired rolling motions of the contact l5 mounted thereon, isplaced fiat on the upper surface of the armature 4i and held in properposition by means of a guiding member 49 which contains a spring forpressing the finger 44 against the armature 4|. The finger 44 has anopening at 45 which is engaged by the projection 48 when the armature 4imoves towards the magnet core 2 and reaches a position slightly prior tothe initial engagement between contacts 5 and IS. The further motion ofthe contact finger 44 is limited to a sliding and partially pivotalmotion about the projection 48 under the exclusion of wiping motions inthe plane of the contact engagement, while the armature is free toperform its overtravel motion under compression of the spring 5|.

Since, as shown in the foregoing, our invention is capable of beingmodified in various forms without departing from its spirit and scope,we wish this specification to be understood as being illustrative andnot in a limiting sense.

We claim as our invention:

1. An electric contactor, comprising a stationary structure having astationary contact, an actuating member pivoted to said structure, acontact finger having a contact to engage said stationary contact andbeing linked to said memher for limited angular motion relative to saidmember, said structure and said finger being adapted to engage eachother during the period of said relative motion and at a point spacedfrom said contacts so as to reduce relative motion between said contactsduring said period.

2. An electric contactor, comprising a station ary structure having astationary contact, an

armature pivoted to said structure, a substan tially rigid contactfinger having a contact to engage said stationary contact and beingresl1= iently mounted on said armature so as to be capa= bio of limitedangular motion relative to said armature, said structure and said fingerbeing adapted to engage each other during the period of said relativemotion and at a point spaced from said contact and being locatedsubstantially in the plane of contact engagement so as to sub-=-stantially prevent relative wiping motion or said contacts during saidperiod.

3. An electric contactor, comprising a station= ary structure having astationary contact, an armature pivoted to said structure, a substan=tially rigid contact finger having a contact to engage said stationarycontact and being resil iently linked to said armature to afford overtravel motion of said armature upon initial en gagement of saidcontacts, said structure having means for engaging said contact fingerduring said overtravel motion at a point between said contacts and theaxis of pivotal motion of said armature.

4. An electric contactor, comprising a stationary structure including amagnet core and a sta-- tionary contact, an armature pivoted to saidstructure in front of said core to be operated thereby, a contact fingerhaving a contact to engage said stationary contact and being resiliently attached to said armature for permitting overtravel motion ofsaid armature relative to said finger when said armature moves intocontact closing position and upon initial engagement between saidcontacts, said finger having a portion spaced from said contacts adaptedto form one part of a pivot joint, and said core having means forengaging said portion during the period of said overtravel so as to formthe other part of the pivot point in order to prevent relative lateralmotions between said contacts after said initial contact engagement.

5. An electric contactor, comprising a stationary structure including amagnet core and a stationary contact, an armature having an opening andbeing pivoted to said structure in front of said core to be operatedthereby, a contact finger having a contact to engage said stationarycontact and being resiliently attached to said armature for permittingovertravel motion of said armature relative to said finger upon initialengagement between said contacts, said finger being located at thearmature side away from 'said core and having a recessed portionadjacent to said opening, and said core having means for pro- Jectingthrough said opening to engage said portion during the period of saidovertravel to prevent wiping motion between the engaging contacts.

WILLIAM G. YOUNG. FERDINAND C. IGLEHART.

